feat: implement DTW comparison, add data segmentation and persistence, and update QML UI for file imports and graphing.

src/pygui/backend/data/local_settings.py

@@ -32,6 +32,9 @@ class LocalSettings:
         self.data_col_count = 0
         self.last_csv_path = ""
 
+        # Session persistence
+        self.session_last_file = ""
+
     # ===== File Path Helpers =====
     @classmethod
     def _settings_path(cls, directory: str) -> Path: